Content search poses one of the most challenging human tasks in the modern life. Content is often searched by computer-assisted metadata searches using a computer and a computer network, particularly when the Internet is being searched as a vast global content store. Metadata extensions to actual content data are a known method to ease data management of large systems. For example Web 2.0 is based on a database where metadata is associated as an extension to actual content data i.e. URI. Known metadata searches are implemented with big server farms. To run a global metadata search is a computation intensive task. Typically all possible associations are returned as search results. Often, the users need to define a new more detailed criterion for further processing based on the search result.
New network technologies are introduced ever faster and also for local data storage. Various types of content such as digital camera images and music files are being stored in computers, set top boxes, music players and mobile phones, for instance. Near field communication (NFC) type systems at present store relatively modest amount of data. There are no known techniques to launch local data searches among RFID tags, for instance, which reside within a communication range. NFC tags are instead treated as separate standalone devices.
Given the quickly falling mass storage price and increasingly popular media recorders and players, the amount of locally stored content is rapidly increasing. Unfortunately, the necessary setup of a well working network access between current and new devices is often technically challenging. Further, portable electrical devices with large (gigabyte) memories may overtake in the future personal computers as main storage and access means for digitized information. Moreover, also passive devices (that is, devices without a power source of their own) possess ever larger non-volatile memories only operable when the devices are externally powered. One example of such a technology is the Radio Frequency IDentification that has been known for more than 25 years. Other proximity communications (that is, inter-device communications between within a range from one millimeter to few meters) technologies include NFC, electronic product code (EPC), ISO 18000-4 and Memory spot by Hewlett Packard corp.
If Moore's law realizes in the future development of passive device memories, a single passive device may store data in the magnitude of a gigabyte. Hence, memory management will be difficult to sustain efficiently. It is seen that both energy and processing time are already precious resources at link protocol layer (Media Access Control, MAC) of passive devices. Yet digital content should be reasonably usable despite the expanding data amounts. While the data transmission rates are also increasing thanks to enhanced compression and transmission technologies, it can also be assessed that accessing desired local content in a reasonable time is becoming ever more challenging. At worst, even if desired data may reside at hand, there is no reasonable access to the data if it cannot be found for using or sharing with others when desired. Let us assume that there is a video or music clip (item) that a home user knows she has somewhere at her home. She may have data storages in her mobile phone, her child's mobile phone, stereo system, set top box, and further a dynamic hard disk on her computer. To find the item, she should search or browse through the contents in each of these devices one by one and item by item (or possibly folder by folder) with the device's own user interface. Alternatively, some existing service and content discovery arrangement such as Universal Plug and Play (UPnP) designed for internet protocol networks could be used so that one device could be used to search into the storage of other devices. However, no such background art disclosure is known and also the search would take long time if every single device contents should be transferred to the searching device, device by device and item by item or folder by folder, until the desired content (item) is found.
It is an object of the invention to avoid or at least mitigate drawbacks of existing data searching and particularly local data searching.